/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.solr.search;

import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queries.function.FunctionValues;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.queries.function.ValueSourceScorer;
import org.apache.lucene.search.IndexSearcher;
import org.apache.solr.search.function.ValueSourceRangeFilter;

import java.io.IOException;
import java.util.Map;

// This class works as either a normal constant score query, or as a PostFilter using a collector
public class FunctionRangeQuery extends SolrConstantScoreQuery implements
		PostFilter {
	final ValueSourceRangeFilter rangeFilt;

	public FunctionRangeQuery(ValueSourceRangeFilter filter) {
		super(filter);
		this.rangeFilt = filter;
	}

	@Override
	public DelegatingCollector getFilterCollector(IndexSearcher searcher) {
		Map fcontext = ValueSource.newContext(searcher);
		return new FunctionRangeCollector(fcontext);
	}

	class FunctionRangeCollector extends DelegatingCollector {
		final Map fcontext;
		ValueSourceScorer scorer;
		int maxdoc;

		public FunctionRangeCollector(Map fcontext) {
			this.fcontext = fcontext;
		}

		@Override
		public void collect(int doc) throws IOException {
			if (doc < maxdoc && scorer.matches(doc)) {
				delegate.collect(doc);
			}
		}

		@Override
		public void setNextReader(AtomicReaderContext context)
				throws IOException {
			maxdoc = context.reader().maxDoc();
			FunctionValues dv = rangeFilt.getValueSource().getValues(fcontext,
					context);
			scorer = dv.getRangeScorer(context.reader(),
					rangeFilt.getLowerVal(), rangeFilt.getUpperVal(),
					rangeFilt.isIncludeLower(), rangeFilt.isIncludeUpper());
			super.setNextReader(context);
		}
	}
}
